1. Field of the Invention
The invention pertains to a rotor for an electrical machine, including a rotor carrier of metallic material with a radially extending back wall and a tubular section extending axially from the back wall, in which a laminated core is installed.
2. Description of the Related Art
Electrical machines are generally known. They comprise a rotor, which rotates around a shaft, and a stator, which is stationary with respect to the rotor. The electrical machine can be, for example, a motor, a generator, or a motor-generator. The latter type of machine is used to an increasing extent in motor vehicle technology to combine previously separate functions or systems, namely, the generator which produces the electrical power for the on-board vehicle electrical system and the starter which starts the internal combustion engine, into a single system. Current developments in the automotive industry demand in general that increasing the comfort of the ride should not lead to any increase—or certainly not to any excessive increase—in the weight of the vehicle and should in fact be associated with a decrease in its weight. The starter-generator has already provided a weight advantage in this context, and efforts are continuing to achieve an even greater weight reduction in this area.
The laminated core of a rotor, which guides a magnetic flux to produce a torque, can be mounted directly on the rotor shaft, for example, or it can be mounted indirectly on the shaft of the electrical machine by means of a rotor carrier and possibly a hub, as is the case with external rotor machines. According to a known process, the rotor carrier is a single part formed by cutting operations out of a solid piece of material such as a cylinder of aluminum or steel. It is also known as an alternative that a circular blank can be welded to a section of tubing to form a rotor carrier. The known processes suffer from the disadvantage that they are too material-intensive and require a great deal of labor, as a result of which their production costs are high.